Aircraft-hazardous incidents that are encountered by landing aircraft consist of meteorological phenomena and aircraft flying in close proximity to the runway. The meterological phenomena includes microbursts, thunderstorms, tornadoes and the wake turbulence of aircraft.
Microbursts, which are also known as windshear, have always been a serious hazard to aviation. The microburst is defined as a powerful downward blast of wind usually associated with a thunderstorm or rain, followed by a violent vertical burst of wind and after touchdown, disperses in all directions, hence windshear. Microbursts typically have diameters of a half mile or less and are short-lived, with ninety percent of the microburst reaching maximum velocity in ten minutes. A region of superheated air some distance above the ground is initially penetrated by rain. The rain evaporates at a high rate to quickly reduce the air temperature and thereby increase the density of the superheated air. The now heavy air proceeds to move downwardly in an accelerating rate until it reaches ground level where it must now spread horizontally. The short-term nature of the microburst occurs because the rapid air fall causes a partial vacuum and thus, as the air drops to the ground and is heated, it returns to reduce that partial vacuum. As additional rain penetrates the region, equilibrium results and the microburst terminates. Wind has been found to gust down vertically at least four thousand feet per minute from distances of two thousand feet from ground level. The basic shape of the microburst, if it could be seen would be like that of an inverted mushroom.
An aircraft flying through a microburst first encounters a headwind that provides good lift. This headwind may be up to fifty miles an hour. Then the aircraft, in a very short space of time and distance, encounters the opposite wind which now becomes a tailwind again at fifty miles an hour in the opposite direction. Thus, the aircraft has now experienced one hundred miles an hour air speed change over distances as short as one mile. If an aircraft is flying flaps down and near landing speed and encounters a tail wind, the pilot experiences a sudden loss of air speed. If adjustments can not be made quickly, or if the plane is so heavily loaded or dragging that it cannot make rapid accommodating changes, the aircraft may crash.
Explained a little differently, an aircraft during takeoff and landing is typically operated near stall speed and the acceleration capabilities on large aircraft are inadequate to cope with large air speed variations. The first symptom of a microburst is a relatively rapid increase in the headwind. This increases the air flow across the wings and if nothing else is changed, the performance of the aircraft will cause it to rise above the desired flight path. The typical pilot would choose to throttle back to reduce power to a safe air speed. Almost immediately a downdraft occurs and the headwind disappears and a strong tailwind becomes prevalent. Because the pilot is now in a powered-down mode, increased air speed to counteract the tailwind is now required. However, the aircraft does not have the acceleration capabilities to cope with this rapid variation and the aircraft stalls and a subsequent crash is quite frequently a common occurrence.
It is important to remember that the only time a microburst becomes a serious hazard is when it appears in close proximity to an airport runway to thereby cause the aircraft to rapidly change altitude in areas where any significant change in altitude is disastrous, once a microburst is detected, the pilot can be warned and could maneuver the aircraft either around the microburst or if knowing what is to occur, the pilot could possibly maneuver the aircraft safely through the microburst.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however the following U.S. patents are considered related:
______________________________________ U.S. PAT. No. INVENTOR ISSUED ______________________________________ 5,262,773 Gordon 16 November 1993 5,257,021 Cornman 26 October 1993 5,111,400 Yoder 5 May 1992 5,105,191 Keedy 14 April 1992 4,994,974 Cummings 19 February 1991 ______________________________________
Andrew Gordon, the applicant of the present invention is also the inventor of U.S. Pat. No. 5,262,773 which is hereby incorporated by reference. The U.S. Pat. No. 5,262,773 patent discloses an invention which displays a discovered microburst on a ground flight controller's monitoring screen in relation to the airport runway and in relation to any aircraft that may be using that runway for take-off or landing. The microburst information is then transmitted by the ground flight controller to the pilot of the aircraft to take appropriate evasive action. However, the disadvantage of this system is that the pilot does not observe the microburst directly and must rely on the information being supplied by the air traffic controller (ATC). The present invention overcomes this disadvantage by displaying within the cockpit of the aircraft the appropriate desirable information of the microburst and other meteorological conditions. Thus, the pilot, himself or herself, can take appropriate evasive action without depending upon the secondary information provided by the ATC.
The U.S. Pat. No. 5,257,021 Cornman patent discloses a low-level wind-shear alert system. The system identifies the presence and locus of the wind shear in a predefined area by mapping the two-dimensional wind velocity, measured at a number of locations, to a geographical indication of the wind shear. The system also integrates data and processed information received from sources such as anemometers and doppler radar, to produce the wind shear alerts.
The U.S. Pat. No. 5,111,400 Yoder patent discloses an integrated real-time aircraft flight-crew information dissemination system. The information includes air traffic and meteorological conditions and stores data concerning terrain and moving map features within the range of an air traffic control facility (ATC). An airborne computer and display for generating a continuously updated graphic display of the dynamic and static conditions. The airborne computer also detects potential collisions with the dynamic or static features and issues a warning based on the level of the collision threat. When a potential collision is detected, the aircraft display isolates the threatening target and provides information to facilitate collision avoidance actions.
The U.S. Pat. No. 5,105,191 Keedy patent discloses an apparatus and a method for detecting and indicating weather conditions for aircraft. The apparatus includes a sensor for detecting the weather parameters of air temperature differential and a computer for comparing the parameter value with a stored constant valve. When the parameter valve exceeds the constant valve, a severe weather condition warning indication in the form of a visual and/or audio signal is generated by the computer.
U.S. Pat. No. 4,994,974 Cummings patent discloses a touch-sensitive navigation system. The system permits the pilot of an aircraft to display on a screen a navigation chart showing the position of the aircraft with respect to fixed environmental checkpoints. The system is also designed to allow the system memory to be quickly updated and is intended to supersede navigation chart manuals.
In summary, none of the other disclosed inventions provide the pilot with real live images of wind in real time which are displayed horizontally, so that the pilot can take immediate evasive action.